Mayor Rahm Emanuel says the teachers strike is "not necessary" because the two sides were close.

"I believe this is avoidable because this is a strike of choice," Emanuel said at a hastily called news conference at the Harold Washington Library Sunday night

Emanuel sought to cast the negotiations as hinging on two remaining issues: a new teacher evaluation system and principals' ability to get rid of teachers. Chicago Teachers Union officials said there are more remaining issues than that, although they conceded the strike is not primarily about money.

The strike on Emanuel's watch could cut against the narrative the mayor is trying to craft as a leader who's a problem solver moving the city forward. It also could set the tone for his somewhat fractured relationship with labor, with his first major union contract negotiation ending in a strike.

Emanuel’s aggressive posture in pushing for a longer school day and year, while also cutting the pay raise teachers were supposed to get last year, galvanized the union. With negotiations being watched carefully on a national basis, the soured relationship may have led union leadership to strike as a way to take a stand against Emanuel's tactics.

Sending Emanuel into negotiations to broker a last-minute deal wasn’t an option because there was so much bad blood between him and Chicago Teachers Union President Karen Lewis, several sources said. Instead, the administration dispatched Board of Education President David Vitale to sit in on talks in the waning days. Vitale helped negotiate teacher contracts in 2003 and 2007, and the union took his hands-on involvement as a sign the district was serious about sealing a deal.

While the mayor kept close tabs behind the scenes, Emanuel has maintained a relatively low public profile since returning from the Democratic National Convention late Wednesday, a trip he cut short. Although he was never at the negotiating table, Emanuel’s physical presence in Chicago provided the mayor with better optics as teacher contract talks continued.

The mayor hasn't had a public schedule since last Tuesday, the first day of school for most Chicago Public School students. Emanuel has, however, been out and about the city. On Friday, he attended a Bruce Springsteen concert at Wrigley Field. On Saturday, he was at the 79th Street Renaissance Festival in Auburn-Gresham and the Renegade Craft Fair in Wicker Park. On Sunday afternoon, Emanuel was spotted at Misercordia's annual fundraiser, where he took at least one question from a high-school student who asked him whether she’d be in school Monday.

“I hope so,” he said.

Ald. Ricardo Munoz said parents in his Southwest Side ward won't lay blame if the two sides do the responsible thing and end the strike quickly. "Look, they've had over 50 negotiating sessions. They need to reach a deal," said Munoz, 22nd.

"The parents in my ward want their kids to be in school. They don't care who's to blame," he said.

Ald. Howard Brookins, 21st, chairman of the City Council's black caucus, said after the union's announcement that he was "mystified" the two sides couldn't reach agreement.

"Especially hearing the union say the main issues separating the two sides aren't financial, I can't figure out why the adults couldn't get together and reach an agreement to benefit the children of this city," Brookins said.

He acknowledged a "gasoline and fire" relationship has developed between Lewis and Emanuel, but said he finds it unlikely the union decided to strike out of some impulse to punish Emanuel for the strident way he has pushed his education agenda over the past several months.

"I really don't think Karen Lewis would take a step like this that will be harmful to the children because of problems with the mayor," Brookins said.

He expressed dismay that the announcement of the strike came so late Sunday, predicting "a lot of scrambling and a lot of chaos" Monday as parents try to figure out what to do with their kids.

"As the two sides continued negotiating late into the day, I figured it was an indication they were close and would get this figured out," he said.

People in his ward "are going to blame both sides," Brookins said. "African American and Hispanic families in this city need the schools open."